MAJOR AQUIFER STUDY 1: METASEDIMENTARY ROCKS, VARIABLY CALCAREOUS

The study areas for major aquifer studies 1 and 2 (MAS 1 and 2) are based on groups of lithogeochemical units, which are classifications of bedrock units with similar mineral composition, texture, and for some bedrock units, relative age (see lithogeochemical data set below). The lithogeochemical groups have different water chemistry characteristics as shown in Ayotte and others (1999). The study location map below shows the location of MAS 1 and MAS 2.

MAS 1 is a network of 28 wells located in a group of lithogeochemical units with a higher occurrence of arsenic in ground water than other groups in the NECB study area (Ayotte and others, 1999). MAS 1 was limited to areas underlain by bedrock units that are comprised of metamorphosed sedimentary rocks derived from carbonate-bearing protoliths. The study was conducted to determine the occurrence and distribution of arsenic in this lithogeochemical group.

The study area extends from east-central Maine, through southeastern New Hampshire, and into north-central Massachusetts (see study location map below). The 28 wells sampled were randomly selected from bedrock wells within the study area boundary that are used to supply water to homes (termed domestic wells) (Scott, 1990). The wells were sampled during the fall of 1999 and summer of 2000.

Study Location Map	Water-Quality Data	Lithogeochemical Data Set
	Important readme file Field data: tab-delimited RDB file MS Excel file Nutrients: tab-delimited RDB file MS Excel file Major Ions: tab-delimited RDB file MS Excel file Trace elements: tab-delimited RDB file MS Excel file VOCs: tab-delimited RDB file MS Excel file Radiochemical/other: tab-delimited RDB file MS Excel file Pesticides: tab-delimited RDB file MS Excel file Well inventory: tab-delimited RDB file MS Excel file

NECB NAWQA Major Aquifer Studies